. I have a 1987 Cadillac Allante both fans stopped working. I have acquired a new module 1641400 will this fix the problem. Or do I have to replace other parts. I have checked the fans. They are working fine, with a jumper wire your help on this issue is most appreciated

MoistCabbage

07-21-12, 04:00 AM

Fuses, relays, temp sensor? What is module 1641400?

carnut

07-21-12, 09:49 AM

In my experience the fan control module behind the passenger headlight affects fan speeds, not causing fans to completely quit. On my 88 the fans would never go to max RPM and the DIC would show an A/C pressure related code. You have paid for a module so try it. Do you have a factory service manual?

jim55

07-21-12, 07:29 PM

the temperature control module , the big one. Under the pressure side headlight, neither fan would operate with the old modular, replaced it with a new one and air-conditioner fan. When in auto comes on, to help cool the radiator. I was told there may be a relay for the main fan somewhere

jim55

07-21-12, 07:32 PM

I purchased a shop manual, but it doesn't cover any troubleshooting

MoistCabbage

07-21-12, 07:52 PM

I purchased a shop manual, but it doesn't cover any troubleshootingA Haynes or Chiltons repair manual, or an actual Helm factory service manual? BIG difference.

carnut

07-22-12, 02:38 AM

The factory manual does diagnose it. You can operate the fans thru the DIC. You can cause them to change RPM. I'm confused? re read post #4 This module (modular) is not a temperature controlling item. It simply starts the fans and changes the fans (both) RPM depending on what the computer reads. I guess you could call it a temp control module but its a fan control module. Hard to believe it needed both a fan and a new module at the same time. Been awhile since I had my 88 and 91, but the 88 used this module but my 91 used a relay. Without the aid of the factory manual, you are just changing parts hoping to fix it. You said earlier that both fans worked when 12 volts were jumpered to them, then you say you replaced the A/C fan?

jim55

07-22-12, 10:11 PM

no I didn't replace the AC fan. I replaced the AC module, because the AC fan inside the car would not come on, and the fan outside the car would not come on. I jump the fans with 12 volts and they work just fine. I replaced the big module behind the passenger side headlight, but the main cooling fan outside the car will not come on. I have checked all the grounds that I can find it still gives me an error message, which reads cooling fan failure. I don't want to just throw parts at it hoping to fix it

jim55

07-23-12, 10:54 PM

. How do you operate, the fans through the DIC

limo1

07-24-12, 04:07 AM

I had similar problem with a fan control module for radiator fans. on my 1985 fleetwood should be same on your model. Module sits behind headlight and basically takes the BCM fan signal and amplifies it to control the speed of the radiator fans. This module also has a feedback signal back to the BCM so it knows if fans are rotating and speed. I was able to fix the module as the parts that go in them are the power FET transistors mounted to the heatsink. I replaced with
Intersel 76137P N channel Power FETS x 4 transistors needed. It looks to me like the originals just do not quite have the current capacity for the two fans. If the fans get a bit sticky they cause more current to draw through the control module and pop the transistors.
Here is datasheet. http://html.alldatasheet.com/html-pdf/52862/FAIRCHILD/HUF76137P3/409/1/HUF76137P3.html

Just open up module and replace the 4 transistors on the heatsink with above and you have a better speed control module than new. These FET's are rated 75A at 30V x 4 lots of current. Also note the heatsink has fan voltage on it so it should be isolated from touching any chassis ground or it would blow the transistors. A cheap fix couple dollars for the parts a solder iron and good as new. Also check for corrosion inside on the foil as water seems to get in.

jim55

07-24-12, 05:34 AM

I do have an old module. I will try this fix, maybe I'll get lucky and have no more problems. I thank you for this solution

jim55

07-25-12, 06:46 PM

I have found the problem. There was a broken wire, way up underneath the car repaired this and everything seems to work as it should I do want to thank everyone who tried to help me with this situation. It is a pleasure to see people coming together in one place to help an individual. Again. Thank you for your assistance

Camille

01-07-14, 11:23 AM

hi,
I have a simular problem.
So I ordered those 4 Power FETS you mentioned and received them quickly. Now I notice that the transistors on the print are not all the same. I have: 1 FET , 2 black transistors (1 on either side), 1 very smal transistor. Are these the ones that I have to replace with those Power FETS?
Thanks for helping.

FLew

08-25-14, 04:40 PM

I had my radiator replaced, the fan didn't work after that. I later found out that the repairman didn't replace the temp switch in the radiator. he just plugged the hole /w a bolt. I removed the bolt and put a temp switch in and plugged it up. fan has worked every since. Good Luck!!!.